Jakarta. Four assailants died and 10 bystanders – four of them police officers – were injured in a suicide bombing at the police headquarters in Surabaya, East Java, on Monday (14/05), officials said.

Kompas TV broadcasted closed-circuit television footage showing the explosion occurring immediately after officers stopped four people approaching a checkpoint outside the police headquarters on two motorcycles.

"We can confirm that there were two-wheel vehicles … at the checkpoint when the blast occurred," East Java Police spokesman Chief Comr. Frans Barung Mangera said at a press conference.

He added that all the victims have been taken to a police hospital following the blast, which occurred at 8:50 a.m.

President Joko "Jokowi" Widodo has meanwhile condemned the attack, describing it as cowardly, undignified and barbaric.

Suicide bombers also targeted three churches in Surabaya on Sunday morning, killing 14 people and injuring 40.

Police confirmed that the six attackers were members of one family, headed by the leader of a cell of the Islamic State-inspired group Jemaah Ansharut Daulah (JAD) in Surabaya.

Sidoarjo Blast

Three people were killed and two injured in another attack on Sunday evening, when a bomb exploded in a low-cost apartment behind a police station in nearby Sidoarjo, East Java.

Frans told the Jakarta Globe that three casualties in the Sidoarjo blast were also from one family – the father, mother and their eldest son – while two other children are currently hospitalized at a police hospital in Surabaya.

National Police chief Gen. Tito Karnavian said the head of the family involved in the Sidoarjo blast had close ties with the head of the family involved in the Surabaya church attacks.

The blast reportedly occurred while the family was assembling the bomb. Police have recovered at least three homemade bombs from the scene.

On Monday, five suspected terrorists were captured, one of them is a JAD Surabaya leader, Tito said.

Top Alert

Since the series of attacks in East Java, several other provinces, including Bali, have also been on the highest level of alert.

The Jakarta Police and the military started night patrols on Sunday night, police spokesman Chief Comr. Argo Yuwono said.

"We will be conducting joint patrols with the military, like we did last night" Argo told reporters, adding that increased security measures have been imposed at all police stations.

Legal Umbrella

The president has called on members of the House of Representatives to pass a counterterrorism bill, which has been pending since February 2016, saying that he will issue a government regulation in lieu of law (Perppu), if they fail to enact the bill this month.